A study of human γ-globulin adsorption capacity of PVDF hollow fiber affinity membranes containing different amino acid ligands

Affinity membranes were prepared with poly(vinylidene fluoride) (PVDF) hollow fibers or flat membranes as the matrix, 1,6-hexanediamine (HDA) as the space arm, and amino acid—l-phenylalanine (l-Phe), l-tryptophane (l-Trp) and l-histidine (l-His) as the hydrophobic ligands, respectively. X-ray photoelectron spectroscopy (XPS) analysis results indicated that the contents of oxygen and nitrogen increased from 5.6% to 16.5% and 0.6% to 3.0% on the membrane surface after l-Phe modification, respectively, while fluoride content decreased from 38.3% to 23.0%. The effects of operation parameters such as pH value and ionic strength, on the human γ-globulin (HGG) adsorption capacity of the affinity membranes were investigated in a batch system. The adsorption phenomena appeared to follow a typical Langmuir adsorption isotherm under the optimal condition, where the maximum adsorption capacity (qm) of l-Phe affinity membrane for γ-globulin was 0.318 mg/cm2 membrane and the equilibrium constant (Kd) value was found to be 0.453 mg/mL solution from the Scatchard plot. Forty hollow fibers with a membrane area of 0.0188 m2 in the membrane module adsorb 21 mg HGG from 10 mL human plasma with a purity of 83.9% in a single-pass mode. And the affinity membrane represented good stability throughout repeated adsorption–elution cycles.